The present invention relates to a new arch ring unit and a method of using the arch ring unit to form new archways particularly but not exclusively for road, rail etc. arches and bridges.
In Northern Ireland alone there are approximately 4,500 bridges having a span of over two meters. Of these approximately 3,500 are masonry arches. Many of these masonry arches are old and indeed historic, but nevertheless must be maintained to a high standard in order to continue to carry traffic. Indeed, in order to continue to carry increasingly large volumes of traffic.
The maintenance of masonry arches is an annual exercise, requiring significant funding and staff time. Complete rebuilding of masonry arches involves complete closure of the relevant intersection, i.e. at least one or two road and rail passageways. Repair is therefore preferred. Extrapolation of the above statistics and considerations to the whole of the British Isles, and indeed beyond, shows the enormity of work involved every year by local road maintenance workers.
One method of strengthening existing masonry arches is to strengthen the arch barrel by guniting. This has important environmental considerations, and for the replacement of masonry arches of modest span, the use of concrete pipes is preferred, and is the most economical method. However, standard concrete pipes have a maximum span of 2 meters. For each different span greater than 2 meters, a different pre-cast mold is required. Moreover, the transportation of concrete arches, having a span of at least two meters, and frequently significantly more, is a major exercise in its own right. Transportation often involves significant traffic considerations, i.e. a large, slow load.
Thus, any significant reduction in repair time, staff times and transportation considerations, would provide significant benefit. Indeed, for the repair and strengthening of many archways, the very high costs of service diversion and replacement often exceeds the cost of the bridge works themselves.